Single polar telegraph circuits



E. F. WATSON SINGLE POLAR TELEGRAPH CIRCUITS June 16, 1925. 1,541,880

Filed NOV. 21. 1921 Jtatz'an J INVENTOR E Z 716M901 Patented June 16*, 1925.

UNITED STATES PATENT OFFICE.

EDWARD F. \VA'I'SON, 0F YONKERS, NEW YORK, ASSIGNOH 330 AMERICAN TELEPHONE AND TELEGRAPH CC'MPANY, A COEJPOEATION OF NEW YORK.

SINGLE POLAR TELEGRAPH CIRCUITS.

Application filed. November 21, 1921. Serial No. 516,370.

To all whom it may concern,

Be it lmown that I, EDWARD F. l VATsoN, residing at Yonkers, in the county o-i lestchester and State of New York, have invented certain Improvements in Single Polar Telegraph Circuits, of which the following is a specification.

This invention relates to telegraph circuits and more particularly to the type of telegraph circuit known as single Morse circuits in which signals are transmitted in but one direction over the same line at one time, although the system is so arranged that signals may be transmitted in either direction.

One of the objects of the invention is to produce a signaling system in which signals may be transmitted in either direction over a line wire without balancing the wire.

Another object of the invention is to produce a signaling system in which signals consisting of positive and negative impulses may be transmitted in either direction over v a line wire without balancing the wire.

Another object of this invention is to produce a system in which the line will be switched into connection with the transmitting apparatus at one end and the receiving apparatus at the other end, but, under suitable conditions, may be switched into connection with the receiving apparatus at the first mentioned end and into connection with the transmitting apparatus at the other end for transmitting singnals in the reverse direction.

Another object of the invention is to pro vide a system in which the stations at each end of the line are provided with a transmitting and a receiving apparatus, the transmitting apparatus at one station being connected with the line and the receiving apparatus at the other station being connectcd with the line when signals are transmitted in one direction, the system being so arranged that, by transmitting a break signal from the station which isireceiving, the

connections may be interchanged to connectthe transmitting apparatus with the line at the receiving station and the receiving apparatus with the line at the transmitting station, whereby signals may be transmitted in the opposite direction.

Another objectot the invention is to produce a system having the characteristics above referred to and which adapted for the transmission of printing telegraph signals.

A still further object of the invention is to provide a system having the characteristics above referred to in which the switch ing apparatus for determining whether the line will be connected to the transmitting or to the receiving apparatus at a given station will be under the control of a relay responsive only to abnormal current conditions in the line.

The above objects as well as other objects 01"- the invention will be clear from the following description thereof when read in connection with the accompanying drawing, Figure 1 of which represents a telegraph system embodying the principles of the invention.

Referring to the diagram, ML designates a main transmission line fora telegraph circuit terminating at opposite ends at two stations indicated as A and B respectively. At station A a local loop L extends to a subscribers station at which suitable transmitting and receiving apparatus may be provided,tor example, the loop L is illustrated as including a schematically indicated transmitting distributor TD of a printing telegraph set and a home recording relay HER of such a set.

The loop L at station A is balanced by means of a balancing circuit or resistance N, and windings of a polar pole changing relay. PG and a polar break release relay BBB are included in the loop L and balancing circuit N. At the junction point between the loop L and the balancing circuit N a connection extends to the armature of a polar receiving relay RE, which relay may, under certain conditions, be associated with the main line ML for transmitting si nals to the loop. a

A transfer relay TB is arranged, so that it may switch the main line ML either into connection with the receiving relay ER or into connection with the transmitting apparatus controlled by the armature of the pole changer PC. A break relay BB is provide'd, said relay having three windings, all connected so that their ellects will be in the same direction magnetically. Two of these windings are controlled through the back and front contacts of the pole changer PC, so that the narlring and spacing currents are transmi ted through these windings.

The third winding is under the control of the armature of the break release relay BBB. The break relay is so arranged that its armature controls the circuit of the transfer relay TR, and the break relay when once energized remains energized until a break signal is transmitted from the receiving station as will be described later. The transfer relay TR will therefore remain energized or be deenergized, depending upon the condition of the break relay, so that when the transmitter at one station is connected to the line and the receiver at the other station is also connected to the line this condition will remain until a break signal is transmitted from the station which is receiving.

The apparatus at station E is identical with that at station A, and corresponding elements are represented by the same ref erencecharacters primed. Further details of the apparatus will be clear from a description of the operation, which is as follows:

As illustrated, the apparatus at stations A and B is in condition for transmitting from the former to the latter. Under these conditions, the break relay BR at station A is energized and maintains the transfer relay TR energized, so that the main line ML is connected to the armature of the pole changer P The transfer relay TR at its lower front contact completes a locking circuit to positive battery for the winding of the receiving relay RR, so that its armature is held against its negative contact. At station. B both the break relay BR and the transfer relay TR are deenergized, so that the winding of the receiving relay HR is connected to the line ML over the upper back contact of the transfer relay.

Underthese conditions above described, when the loop L is closed current flows from the positive battery through the winding of the home recording relay HER, through the transmittingdistributor TD, through the loop winding of the break release relay BER and pole changer PC and over the contact of the receiving relay RR to negative battery. Current also flows from ground through the balancing resistance N, balancing windings of the break release relay BRR and pole changer PC and over the contact of the receiving relay RR to negative battery. Obviously the current flowing through the loop windings of the pole changer and the break release relay is sub stantially twice as great as that flowing through the balancing windings owing to the fact that the positive and negative batteries are connected in series with respect to the loop circuit. The tendency of the current flowing through the balancing windings is to shift the armatures of the pole changer PC and the break release relay BRR to their upper contacts, but owing to the greater pull in the opposite direction produced by the loop windings of said relays, the arinatures are held to their lower contacts, so that negative battery is connected through the lower winding of the break relay BR, over the lower contact of the pole changer PC and over the upper front contact of the transfer relay TR to the main line ML. The resultant line current flows over the upper back contact of the transfer relay T '1 at station E and through the windings of the receiving relay RR to ground. The arn'lature of the receiving relay RR is therefore held against its negative contact, and the current conditions in the loop circuit L are the same as described at station A, so that the contact of the break release reiay ERR is held open. The contact of the pole changer PC controlling the circuit through the lower winding of the break relay BR is also closed, but as this circuit is opened at the contact of the transfer relay TR, the break relay ER is not affected.

The conditions just described obtain dur ing the transmission of marking signals. hen a spacing signal is to be transmitted, the loop L will be opened by means of the transmitting distributor TD at station A, so that no current flows through the loop windings of the pole changer PC and the break release relay ERR. The balancing windings of these relays now become effective, thus shifting their armatures. The shifting of the armature of the break release relay closes a circuit through the upper winding of the break relay BR, and the shifting of the armature of the pole changer PC closes a circuit from positive battery, through the middle winding of the break relay, over the upper contact of the pole changer PC and over the upper front contact of the transfer relay TR to the main line ML, so that the receiving relay RB. shifts its armature to its positive contact. Positive battery is now connected to both ends of the loop L, so that no current flows through the loop windings of the pole changer PC, the break release relay BBB and the winding of the home recording relay ERR. Current flows through the balancing windings of the relays PC and Bill? in the opposite direction, so that these windings are now energized in such a manner as to tend to hold their ai'inatures against their lower contacts. Consequently, the shifting of the battery connections by means of the relay RR is without effect upon the armatures of the pole changer P and the break release relay BER.

The home recording relay HER may function as a sounder where the circuit is use-d fer the transmission of ordinary Morse signals. If a printer is to be controlled by lie) the loop L, however, the firstspace signal of a group Wlll be used to release the receiving distributor (not shown) of the-printer. "Consequently, when therelay HRRis deenergized by reason of the fact that positivebatteryis connected to both ends ofthe loop during the first space signal of the group, the release of its armature will con--' trol the release of the receiving distributor in a well-knownmanner.

It will be noted that during the operations above described the relay BB is maintained energized by current through some one of its windings during the transmission of marking and spacing signals. If,.now,

while signals are being transmitted from station A, it is desired to transmitsignals from stationB, the loop circuit L may be opened, as, for example, by means of the break key. BK. As soon as a negative or marking signal is received from station A, negative battery .Wlll be connected, to the loop over the lefthand contact o flthereceiving relay RR. As the loop windings.

of the pole changer PC"andthe break release relay BER" arefdeenergized, the bal- I ancing windings become effective to shift their armatures to their upper contacts.

Theshilting of thearmature'of the break release relay ERR closes the circuit through the upperwinding ofthe break relay BR thereby energizing"saidrelay, which, at its upper front contact, completes the circuit .for the transfer relay TR. Thetranster relay TR at its lower front contact com olete s a holdino circuit for the receivin O b relayRR' to maintain its armature against its negative contact. At its upper front contact the relay TB connects the main line Ml; over the "upper contact of the pole changer PC and through the middle winding of the break relay BR to negativebattery. Negative battery is now connected to bothends of themain line ML at station A through the lower wind ng of thebreak relay BR and atstation B through the middle Winding of the break relay BR. As a consequence, no current flowsthrough these two windings, and as the break relay BR dependsat this moment for its energization upon its lower winding, said relay will be deenergized and release the transter relay TR. The break relay BR at station B, however, i will be malntained energized through its upper winding under the control of the break release relay BBB/as long the break key BK is held open. The

transfer relay TR at station A, upon being released, disconnects the line 'ML from the contact ofthe pole changer PC and connects it to the winding of the receiving relayRR. As negative spacing current is beingtransmitted over ,the l ne ML front the station E during'the breaking condition, the receiving relay shifts its armature to its. positive contact, so that the pole changer PG and the break release relay BRR willv hold their armatures in their lower positions regardless of whether the loop L is open or closed. No currentcan flow in the loop L under these conditions,

i and in the case of a printing apparatus this COIldltlOIl results 1n stopping the transmitter at the end of its cycle. The break key BK may then berestored, whereupon the armatures of the pole changer PC" and BRR will be shifted to their lower positions. The break relay 131% will now be energized throughits lower. winding, and positive current will be transmitted through this winding to the main line ML. The positive current in this instance constitutes the marking signal,and it will therefore be noted that the direction of current flow with respect to the line is the same for thetransdeenergizing the break relay ER in a manner similar to that already described. The detailsof this. operation will be clear without ifurther consideration.

It,will be obvious thatthe general principles herein [disclosed maybe embodied in many other organizations Widely different from those illustrated without departing from thespirit of the invention as defined in the followingclaims.

fVVhat is claimed is I In a signaling system, 'a line circuit,

terminal stations at each end of said line circuit, each terminal station having trans- 1n1tt1ng apparatus and rece1v1ng apparatus tl 1ereat,switching devices at each station for connecting the transmitting apparatus tolthe line at one station and the receiving apparatus to theline at the second station during non-signaling condition, so that signaling current may be transmitted over the line toone station, means for normally maintaining said connections during times that. no signals arebeing transmitted in either direction, means controlling said switching devices to connect the transmitting apparatus to the line at the second station and the. receiving apparatus to the line at the first" station in responseto the actuation of said transmitting apparatus at said "second station to transmit signaling currents to the other station, said means coinprising break relays at each station lorcon- LIX trolling such switching devices, the break relay atone'stationbeing maintained energlzed by ordinary, signallngcurrents, and .the break relay atgthe, otherstat on bemg deenergized during the transmission ofsignaling currents.

2. In a signaling system, a line circuit, terminal stations at each end of said l ne circuit, each terminal station havmg trans- ,mitting apparatus and receiving apparatus thereat, switching devices at each station for connecting the transmitting apparatus to the line at onestation and the receiving apparatus to the line at the second station during nonsignaling condition, so that signaling current may be transmitted over the line to one station, means for normally maintaining said connections during times that no signals are being transmitted in either direction, ,means controlling said switching devices to connect the transmit ting apparatusto the line at thesecond statlon and the receivlng apparatus to thehne at the first station in response'to the actuation of said transmitting apparatus atsaid terminal stations at each endot saidline circuit, each terminal station having transmitting apparatus and receiving,apparatus thereat, switching devices at each station for connecting the transmitting apparatus to the line at onestation and the receiving apparatusto the-line at the secondstation during no-nsignaling condition, so that signaling current may be transmitted, over the lineto one. station, means for normally maintaining said connections during times that no signals arebeingtransmitted in either direction, means controlling said switching devices to connect the transmittingapparatus to the line at the second station an-'dthe receiving apparatus to the line at the first station in response to the actuation of said transmitting apparatus at saidsecond station to transmit signalingcurrents to the other-station, said means comprlsingbreak relays at each stationfor controlling said switching devices, each break relay having a plurality of windings,,and means for transmitting signaling currents through the windings. of one break relay-to,maintaiirit energized during the transmissionof signals, the windings of the other break relay being deenergized,

to transmit signaling currents JsIna signaling system, a line circuit, termmal stations at each end of said line c rcult each terminal statlon havlng trans- ,mitting.apparatus and receiving apparatus thereat, switch ing devices at each station for connecting the transnnttlng apparatus .to the llne at one statlon and the receiving :apparatus to the line'at the second station .durmg non-slgnahng cond1t1on, so that signaling current may be transmitted from the line to one station, means for normally maintaining said connections during times that no signals are being transmitted in either .direction,.means controlling said switching devices'to connect the transmitting apparatus to the line at the second station and the receivlng apparatus to the line at the first stationin response to the actuation of said transmitting apparatus at said second station to the other station, said, means comprlsing break relays ,at each station for controlling said switch ,ing devices, each break relay havlng a plurality of windings, means for transmitting signaling currents through the windlngs of one break relay to maintam it energized during the transmission of sig- -na1s,the windings of the other break relay being deenergized, and means for energizing the latter relay and deenergizing the former relay atvwill for changing the connections of said switching devices.

5. In a signaling system, a line circuit, terminal stations at each end of said line circuit, each terminal station having transmitting apparatus and receiving apparatus thereat, switching devices at each station for connecting the. transmitting apparatus to the line at one station and the receiving apparatus to the line at the second station, so that signaling currents may be transmitted over the line'to one station, said switching devices alsofunctioning to connect the transmitting apparatus to the line at the second station and the receiving apparatus to the line at the first station to transmit signaling currents to the other station, a break relay to each-station for controlling said switching devices, each break relay having windings through which signaling currents may be transmitted and an additional winding for initially energizing said relay, and means whereby when one of said break rclays has been energized through one of its windings signaling currents may be transmitted through its other windings to maintain its energization while the break relay at the other station will be deenergized.

6. In .a signaling system, a line circuit, terminal stationsvat each end of said line circuit, each terminal station having transmittingapparatus and receiving apparatus thereat, switching devices at each station for connecting the transmitting apparatus to the line at one station and thereceiving apparatus to the line at the second station, so that signaling currents may be transmitted over the line to one station, said switching devicesalso functioning to connect the transmitting apparatus to the line at the second station and the receiving apparatus to the line at the first station to transmit signaling currents to the other station, a break relay at each station for controlling said switching devices, each break relay having windings through which signaling currents may be transmitted and an additional wind ing for initially energizing said relay, means whereby when one of said break relays has been energized through one of its windings, signaling currents may be transmitted through its other windings to vmaintain its energir-aation while the break relay at the other station will be deenergized and means whereby said lastmentioned break relay may be initially energized at will through that signaling currents may be transmitted over the line to one station, said switching devices also functioning to connect the transmitting apparatus to the line at the second station and the receiving apparatus to the line at the first station to transmit signaling currents to the other station, a break relay at each station for controlling said switching devices, each break relay having windings through which signaling currents may be'transmitted and an additional winding for initially energizing said relay, means whereby when one of said break relays has been energized through one of its windings signaling currents may be transmitted through its other windings to maintain its energization while the break relay at the other station will be deenergized, and means to energize said last mentioned relay at will through one of its windings to shift the connections of one of said switching devices, thereby connecting one terminal of the line through another winding of said relay to a current source opposing the signaling current transmitted through a winding of the distant break relay, thereby deenergizing the latter and shifting the connections of the other switching devices.

In testimony whereof, I have signed my name to this specification this 19th day of November 1921.

EDWARD F. WATSON. 

